Although the concept of rivalry is widely recognized as a contributing factor to consumer demand for sporting events, who constitutes a rival and to what degree rivalry influences attendance remains vague. Previous demand models consistently included rivalry as an explanatory variable but represented rivalry in inconsistent ways that often violated rivalry’s core properties (i.e., non-exclusive, continuous in scale, and bidirectional). This study reviews past specifications for rivalry and tests multiple rivalry variables, including a 100-point allocation measure that conforms to rivalry’s core properties, in attendance demand models for both Major League Soccer and the National Hockey League. Results across models generally favor the 100-point measure to represent the special attention fans give to certain opponents. This fan-derived rivalry representation offers researchers, marketers, event managers, and sponsors a more complete picture of rivalry as related to demand estimation for purposes such as promotional planning, game scheduling, and event security protocol.